package api

import (
	"encoding/json"
	"errors"
	"io/fs"
	"log/slog"
	"net/http"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/go-chi/cors"
	"github.com/sandrodach/mindsift/internal/auth"
	"github.com/sandrodach/mindsift/internal/collab"
	"github.com/sandrodach/mindsift/internal/config"
	"github.com/sandrodach/mindsift/internal/domain"
	"github.com/sandrodach/mindsift/internal/storage"
	"github.com/sandrodach/mindsift/internal/ws"
)

type Server struct {
	cfg      *config.Config
	store    *storage.Store
	wsHub    *ws.Hub
	staticFS fs.FS

	leases   *collab.LeaseManager // block leases and open sessions of notes
	notifier *collab.Notifier     // wakes long-poll requests on note changes

	demo demoState // periodic reset in demo mode (demo.go)
}

func NewServer(cfg *config.Config, store *storage.Store, wsHub *ws.Hub, staticFS fs.FS) *Server {
	srv := &Server{
		cfg:      cfg,
		store:    store,
		wsHub:    wsHub,
		staticFS: staticFS,
		leases:   collab.NewLeaseManager(nil),
		notifier: collab.NewNotifier(),
	}
	wsHub.SetRoomAuthorizer(srv.canJoinRoom)
	// Next occurrences of repeating tasks appear live on every connected client
	store.OnTaskCreated = func(th *domain.Thought) {
		srv.wsHub.BroadcastToUsers(srv.taskAudience(th), "TASK_CREATED", th)
	}
	go srv.startAlarmTicker()
	go srv.startCompaction()
	if cfg.DemoMode && cfg.DemoResetMinutes > 0 {
		go srv.startDemoResetTicker()
	}
	return srv
}

// canJoinRoom allows realtime rooms only to users with read access: "doc:<id>" for notes, otherwise a shared list ID.
func (s *Server) canJoinRoom(userID, room string) bool {
	if docID, ok := strings.CutPrefix(room, "doc:"); ok {
		return s.store.DocRole(userID, docID) != ""
	}
	_, err := s.store.GetListByID(userID, room)
	return err == nil
}

// taskAudience returns everyone who can see a task: its owner plus all users of its task list.
func (s *Server) taskAudience(th *domain.Thought) []string {
	if th == nil {
		return nil
	}
	return append(s.store.GetTaskListUserIDs(th.TaskListID), th.UserID)
}

func (s *Server) Router() http.Handler {
	r := chi.NewRouter()

	r.Use(middleware.RealIP)
	r.Use(s.demoResetGate)
	r.Use(middleware.Recoverer)
	r.Use(s.apiLoggingMiddleware)
	r.Use(cors.Handler(cors.Options{
		AllowedOrigins:   []string{"*"},
		AllowedMethods:   []string{"GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"},
		AllowedHeaders:   []string{"Accept", "Authorization", "Content-Type", "X-API-Key"},
		ExposedHeaders:   []string{"Link"},
		AllowCredentials: true,
		MaxAge:           300,
	}))

	// Public Health, Setup & Auth Routes
	r.Get("/api/v1/health", s.handleHealth)
	r.Get("/api/v1/auth/status", s.handleAuthStatus)
	r.Get("/api/v1/legal/{type}", s.handleLegalText)
	r.Post("/api/v1/auth/setup", s.handleFirstBootSetup)
	r.Post("/api/v1/auth/register", s.handleRegister)
	r.Post("/api/v1/auth/login", s.handleLogin)
	r.Post("/api/v1/auth/quickstart", s.handleQuickStart)
	r.Post("/api/v1/auth/forgot-password", s.handleForgotPassword)
	r.Post("/api/v1/auth/reset-password", s.handleResetPassword)
	r.Post("/api/v1/webhooks/ingest", s.handleWebhookIngest)
	r.Get("/api/v1/ws", s.handleWebSocket)
	r.Get("/api/v1/ws/spaces/{spaceId}", s.handleWebSocket)
	r.Get("/api/v1/ws/lists/{listId}", s.handleWebSocket)
	r.Get("/api/v1/events", s.handleSSE)

	// Authenticated API Routes
	r.Group(func(r chi.Router) {
		r.Use(s.authMiddleware)

		r.Get("/api/v1/auth/me", s.handleMe)
		r.Post("/api/v1/events/rooms", s.handleSSERooms)
		r.Post("/api/v1/auth/logout", s.handleLogout)
		r.Post("/api/v1/auth/revoke-all", s.handleRevokeAllSessions)
		r.Patch("/api/v1/auth/settings", s.handleUpdateUserSettings)
		r.Post("/api/v1/auth/alarms/test", s.handleTestUserAlarm)
		r.Get("/api/v1/users/directory", s.handleGetUsersDirectory)
		r.Get("/api/v1/collaborators", s.handleGetCollaborators)
		r.Get("/api/v1/stats", s.handleStats)
		r.Get("/api/v1/search", s.handleSearch)
		r.Get("/api/v1/export", s.handleExport)
		r.Get("/api/v1/export/markdown", s.handleExportMarkdown)
		r.Post("/api/v1/import/mindsift", s.handleImportMindSift)
		r.Delete("/api/v1/user/data", s.handlePurgeOwnData)
		r.Delete("/api/v1/user/account", s.handleDeleteOwnAccount)
		r.Post("/api/v1/import/obsidian", s.handleImportObsidian)
		r.Get("/api/v1/themes", s.handleGetThemes)
		r.Post("/api/v1/themes", s.handleSaveTheme)
		r.Delete("/api/v1/themes/{id}", s.handleDeleteTheme)

		// Instant Capture & Thoughts
		r.Post("/api/v1/inbox", s.handleCaptureInbox)
		r.Get("/api/v1/thoughts", s.handleGetThoughts)
		r.Get("/api/v1/thoughts/{id}", s.handleGetThought)
		r.Patch("/api/v1/thoughts/{id}", s.handleUpdateThought)
		r.Delete("/api/v1/thoughts/{id}", s.handleDeleteThought)
		r.Delete("/api/v1/thoughts/discarded/purge", s.handlePurgeDiscarded)

		// Tinder-Style Triage & Tasks
		r.Get("/api/v1/triage/deck", s.handleGetTriageDeck)
		r.Patch("/api/v1/triage/{id}", s.handleTriageAction)
		r.Get("/api/v1/tasks", s.handleGetTasks)
		r.Post("/api/v1/tasks/{id}/unlink", s.handleUnlinkEnhancedTask)
		r.Post("/api/v1/tasks/reorder", s.handleReorderTasks)
		r.Post("/api/v1/task-lists/{id}/tasks/reorder", s.handleReorderTasks)

		// Task Lists & Shares
		r.Get("/api/v1/task-lists", s.handleGetTaskLists)
		r.Post("/api/v1/task-lists", s.handleCreateTaskList)
		r.Put("/api/v1/task-lists/{id}", s.handleUpdateTaskList)
		r.Delete("/api/v1/task-lists/{id}", s.handleDeleteTaskList)
		r.Get("/api/v1/task-lists/{id}/shares", s.handleGetTaskListShares)
		r.Post("/api/v1/task-lists/{id}/shares", s.handleCreateTaskListShare)
		r.Delete("/api/v1/task-lists/{id}/shares/{shareId}", s.handleDeleteTaskListShare)

		// Workspace Documents & Folders
		r.Get("/api/v1/folders", s.handleGetFolders)
		r.Post("/api/v1/folders", s.handleCreateFolder)
		r.Post("/api/v1/folders/move", s.handleMoveFolder)
		r.Delete("/api/v1/folders", s.handleDeleteFolder)

		r.Get("/api/v1/workspace/folders/shared", s.handleGetSharedFolders)
		r.Post("/api/v1/workspace/folders/shared", s.handleCreateSharedFolder)
		r.Get("/api/v1/workspace/folders/shared/{id}", s.handleGetSharedFolderByID)
		r.Delete("/api/v1/workspace/folders/shared/{id}", s.handleDeleteSharedFolder)
		r.Put("/api/v1/workspace/folders/shared/{id}/mount", s.handleUpdateFolderMount)
		r.Get("/api/v1/workspace/folders/shared/{id}/shares", s.handleGetFolderShares)
		r.Post("/api/v1/workspace/folders/shared/{id}/shares", s.handleCreateFolderShare)
		r.Delete("/api/v1/workspace/folders/shared/{id}/shares/{shareId}", s.handleDeleteFolderShare)

		// Workspace Tags & Pages
		r.Get("/api/v1/workspace/tags", s.handleGetWorkspaceTags)
		r.Get("/api/v1/workspace/tags/{tag}", s.handleGetTagDetails)
		r.Put("/api/v1/workspace/tags/{tag}/note", s.handleUpdateTagPageNote)

		r.Get("/api/v1/documents", s.handleGetDocuments)
		r.Post("/api/v1/documents", s.handleCreateDocument)
		r.Get("/api/v1/documents/{id}", s.handleGetDocument)
		r.Put("/api/v1/documents/{id}", s.handleUpdateDocument)
		r.Put("/api/v1/documents/{id}/move", s.handleMoveDocument)
		r.Delete("/api/v1/documents/{id}", s.handleDeleteDocument)
		r.Get("/api/v1/documents/trash", s.handleGetTrash)
		r.Delete("/api/v1/documents/trash", s.handleEmptyTrash)
		r.Post("/api/v1/documents/{id}/restore", s.handleRestoreDocument)
		r.Get("/api/v1/documents/{id}/backlinks", s.handleGetBacklinks)
		r.Delete("/api/v1/documents/{id}/permanent", s.handlePurgeDocument)
		r.Post("/api/v1/documents/{id}/blocks/{blockId}/enhanced-task", s.handleCreateEnhancedTask)

		// Collaborative note editing (operation log)
		r.Get("/api/v1/docs/{id}/snapshot", s.handleDocSnapshot)
		r.Post("/api/v1/docs/{id}/sync", s.handleDocSync)
		r.Get("/api/v1/docs/{id}/changes", s.handleDocChanges)
		r.Post("/api/v1/docs/{id}/leave", s.handleDocLeave)

		// Document Sharing & Collaboration
		r.Get("/api/v1/documents/{id}/shares", s.handleGetDocShares)
		r.Post("/api/v1/documents/{id}/shares", s.handleCreateDocShare)
		r.Delete("/api/v1/documents/{id}/shares/{userId}", s.handleDeleteDocShare)

		// Shared Lists & Realtime Collaboration
		r.Get("/api/v1/lists", s.handleGetAllLists)
		r.Post("/api/v1/lists", s.handleCreateList)
		r.Get("/api/v1/lists/{id}", s.handleGetListByID)
		r.Delete("/api/v1/lists/{id}", s.handleDeleteList)
		r.Get("/api/v1/lists/{id}/shares", s.handleGetListShares)
		r.Post("/api/v1/lists/{id}/shares", s.handleCreateListShare)
		r.Delete("/api/v1/lists/{id}/shares/{shareId}", s.handleDeleteListShare)
		r.Post("/api/v1/lists/{id}/items", s.handleCreateListItem)
		r.Patch("/api/v1/lists/{id}/items/{itemId}", s.handleToggleListItem)
		r.Put("/api/v1/lists/{id}/items/{itemId}", s.handleUpdateListItem)
		r.Delete("/api/v1/lists/{id}/items/{itemId}", s.handleDeleteListItem)
		r.Post("/api/v1/lists/{id}/items/reorder", s.handleReorderListItems)
		r.Put("/api/v1/lists/{id}/items/reorder", s.handleReorderListItems)
		r.Post("/api/v1/lists/{id}/clear-completed", s.handleClearCompletedItems)

		// Groups (user-managed; stored as teams)
		r.Get("/api/v1/teams", s.handleGetUserTeams)
		r.Post("/api/v1/teams", s.handleCreateTeamDirect)
		r.Put("/api/v1/teams/{id}", s.handleUpdateTeam)
		r.Delete("/api/v1/teams/{id}", s.handleDeleteTeam)
		r.Post("/api/v1/teams/{id}/members", s.handleAddTeamMember)
		r.Put("/api/v1/teams/{id}/members/{userId}", s.handleUpdateTeamMemberRole)
		r.Delete("/api/v1/teams/{id}/members/{userId}", s.handleRemoveTeamMember)

		// API Keys Management
		r.Get("/api/v1/keys", s.handleGetAPIKeys)
		r.Post("/api/v1/keys", s.handleCreateAPIKey)
		r.Delete("/api/v1/keys/{id}", s.handleDeleteAPIKey)

		// Staff Routes (Server-Admin)
		r.Group(func(r chi.Router) {
			r.Use(s.staffMiddleware)
			r.Get("/api/v1/admin/users", s.handleAdminGetUsers)
			r.Post("/api/v1/admin/users", s.handleAdminCreateUser)
			r.Patch("/api/v1/admin/users/{id}", s.handleAdminUpdateUser)
			r.Put("/api/v1/admin/users/{id}/password", s.handleAdminResetPassword)
			r.Delete("/api/v1/admin/users/{id}", s.handleAdminDeleteUser)

			r.Get("/api/v1/admin/invites", s.handleAdminGetInvites)
			r.Post("/api/v1/admin/invites", s.handleAdminCreateInvite)
			r.Delete("/api/v1/admin/invites/{id}", s.handleAdminDeleteInvite)
		})

		// Server-Admin Strictly Protected Routes
		r.Group(func(r chi.Router) {
			r.Use(s.adminMiddleware)
			r.Get("/api/v1/admin/settings", s.handleAdminGetSettings)
			r.Put("/api/v1/admin/settings", s.handleAdminUpdateSettings)
			r.Get("/api/v1/admin/settings/sharing-impact", s.handleAdminSharingImpact)

			// Organizations decide who can see whom; only server admins manage them
			r.Get("/api/v1/admin/organizations", s.handleAdminGetOrganizations)
			r.Post("/api/v1/admin/organizations", s.handleAdminCreateOrganization)
			r.Put("/api/v1/admin/organizations/{id}", s.handleAdminRenameOrganization)
			r.Delete("/api/v1/admin/organizations/{id}", s.handleAdminDeleteOrganization)
			r.Put("/api/v1/admin/users/{id}/organization", s.handleAdminSetUserOrganization)
			r.Post("/api/v1/admin/smtp/test", s.handleAdminTestSMTP)
		})
	})

	// Embedded Frontend SPA Handler
	if s.staticFS != nil {
		fileServer := http.FileServer(http.FS(s.staticFS))
		r.Get("/*", func(w http.ResponseWriter, req *http.Request) {
			path := strings.TrimPrefix(req.URL.Path, "/")
			if path == "" {
				path = "index.html"
			}
			if _, err := fs.Stat(s.staticFS, path); err != nil {
				if strings.HasPrefix(path, "assets/") || strings.HasSuffix(path, ".js") || strings.HasSuffix(path, ".css") {
					http.NotFound(w, req)
					return
				}
				req.URL.Path = "/"
				path = "index.html"
			}
			if path == "index.html" || path == "sw.js" || path == "manifest.json" {
				w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate")
				w.Header().Set("Pragma", "no-cache")
				w.Header().Set("Expires", "0")
			}
			if path == "index.html" {
				if data, err := fs.ReadFile(s.staticFS, "index.html"); err == nil {
					scheme := "http"
					if req.TLS != nil || req.Header.Get("X-Forwarded-Proto") == "https" {
						scheme = "https"
					}
					host := req.Header.Get("X-Forwarded-Host")
					if host == "" {
						host = req.Host
					}
					if host != "" {
						origin := scheme + "://" + host
						htmlStr := string(data)
						htmlStr = strings.ReplaceAll(htmlStr, `content="/og-image.png"`, `content="`+origin+`/og-image.png"`)
						htmlStr = strings.ReplaceAll(htmlStr, `property="og:url" content="/"`, `property="og:url" content="`+origin+`/"`)
						data = []byte(htmlStr)
					}
					w.Header().Set("Content-Type", "text/html; charset=utf-8")
					w.WriteHeader(http.StatusOK)
					_, _ = w.Write(data)
					return
				}
			}
			fileServer.ServeHTTP(w, req)
		})
	}

	return r
}

// --- HELPERS & MIDDLEWARE ---

func writeJSON(w http.ResponseWriter, status int, data interface{}) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(data)
}

func writeError(w http.ResponseWriter, status int, message string) {
	writeJSON(w, status, map[string]string{"error": message})
}

// writeStoreError maps read-only task list violations to 403 and everything else to the given fallback status.
func writeStoreError(w http.ResponseWriter, fallbackStatus int, err error) {
	if errors.Is(err, storage.ErrTaskListReadOnly) || errors.Is(err, storage.ErrAssigneeNoAccess) {
		writeError(w, http.StatusForbidden, err.Error())
		return
	}
	writeError(w, fallbackStatus, err.Error())
}

func (s *Server) apiLoggingMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Only log API requests (/api/...)
		if !strings.HasPrefix(r.URL.Path, "/api") {
			next.ServeHTTP(w, r)
			return
		}

		start := time.Now()
		ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)

		next.ServeHTTP(ww, r)

		duration := time.Since(start)
		durationMs := float64(duration.Microseconds()) / 1000.0
		status := ww.Status()
		if status == 0 {
			status = http.StatusOK
		}

		method := r.Method
		path := r.URL.Path

		if status >= 500 {
			slog.Error("HTTP request failed",
				"method", method,
				"path", path,
				"status", status,
				"duration_ms", durationMs,
			)
		} else if status >= 400 {
			slog.Warn("HTTP request warning",
				"method", method,
				"path", path,
				"status", status,
				"duration_ms", durationMs,
			)
		} else {
			slog.Debug("HTTP request completed",
				"method", method,
				"path", path,
				"status", status,
				"duration_ms", durationMs,
			)
		}
	})
}

// authenticateToken resolves a session JWT or an API key (mindsift_sec_…) to an active user. JWTs are
// checked against the revocation list and token_version; viaAPIKey tells the caller which it was.
func (s *Server) authenticateToken(token string) (user *domain.User, viaAPIKey bool) {
	token = strings.TrimSpace(token)
	if token == "" {
		return nil, false
	}
	if strings.HasPrefix(token, "mindsift_sec_") {
		u, err := s.store.ValidateAPIKeyAndGetUser(token)
		if err != nil || u == nil || !u.IsActive {
			return nil, true
		}
		return u, true
	}
	claims, err := auth.ValidateToken(s.cfg.JWTSecret, token)
	if err != nil || claims == nil || s.store.IsTokenRevoked(token) {
		return nil, false
	}
	u, err := s.store.GetUserByID(claims.UserID)
	if err != nil || u == nil || !u.IsActive {
		return nil, false
	}
	if claims.TokenVersion != 0 && claims.TokenVersion != u.TokenVersion {
		return nil, false
	}
	return u, false
}

// apiKeyAllowed: until API keys get scopes, a key has exactly one right – delivering data into MindSift
// (POST /api/v1/inbox; /api/v1/webhooks/ingest authenticates on its own). Everything else needs a login.
func apiKeyAllowed(r *http.Request) bool {
	return r.Method == http.MethodPost && r.URL.Path == "/api/v1/inbox"
}

func (s *Server) authMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		token := ""
		if authHeader := r.Header.Get("Authorization"); strings.HasPrefix(authHeader, "Bearer ") {
			token = strings.TrimPrefix(authHeader, "Bearer ")
		} else {
			token = r.Header.Get("X-API-Key")
		}
		user, viaAPIKey := s.authenticateToken(token)
		if user == nil {
			writeError(w, http.StatusUnauthorized, "Nicht autorisiert – bitte anmelden")
			return
		}
		if viaAPIKey && !apiKeyAllowed(r) {
			writeError(w, http.StatusForbidden, "API-Keys dürfen nur Daten einliefern (POST /api/v1/inbox oder /api/v1/webhooks/ingest)")
			return
		}
		next.ServeHTTP(w, r.WithContext(auth.WithUserID(r.Context(), user.ID)))
	})
}

func (s *Server) staffMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		userID := auth.GetUserID(r.Context())
		if userID == "" {
			writeError(w, http.StatusUnauthorized, "Nicht autorisiert")
			return
		}
		user, err := s.store.GetUserByID(userID)
		if err != nil || user == nil || user.Role != "admin" {
			writeError(w, http.StatusForbidden, "Admin-Berechtigung erforderlich")
			return
		}
		next.ServeHTTP(w, r)
	})
}

func (s *Server) adminMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		userID := auth.GetUserID(r.Context())
		if userID == "" {
			writeError(w, http.StatusUnauthorized, "Nicht autorisiert")
			return
		}
		user, err := s.store.GetUserByID(userID)
		if err != nil || user == nil || user.Role != "admin" {
			writeError(w, http.StatusForbidden, "Server-Administrator-Rechte erforderlich")
			return
		}
		next.ServeHTTP(w, r)
	})
}